Low Total CO2 Research Articles

Heat stress affects dairy cow health status through blood oxygen availability

BackgroundRises in global warming and extreme weather occurrence make the risk of heat stress (HS) induced by high ambient temperatures more likely in high-yielding dairy cows, resulting in low milk quality and yield. In animals, oxygen is involved in many physiological and metabolic processes, but the effects of HS on oxygen metabolism remain unclear. Thus, the current study aimed to investigate how oxygen metabolism plays a role in health status of dairy cows by measuring the milk yield, milk composition, and blood biochemical variables of cows under different levels of HS: none (No-HS), mild (Mild-HS), and moderate HS (Mod-HS).ResultsThe HS significantly increased rectal temperature (Ptreat < 0.01) and respiration rate (Ptreat < 0.01). Under Mod-HS, greater Na+ (P < 0.05) and lower total CO2, and pH (P < 0.05) were observed relative to those under No-HS and Mild-HS. Oxygen concentrations in both coccygeal artery and mammary vein (Ptreat < 0.01) were lower under Mod-HS than under No-HS. Coccygeal vein concentrations of heat shock protein 90 (HSP90) (P < 0.05) increased during Mod-HS compared with those in cows under No-HS. Malondialdehyde increased during Mod-HS, and glutathione peroxidase (P < 0.01) increased during Mild-HS. Coccygeal vein concentrations of vascular endothelial growth factor (P < 0.01), heme oxygenase-1 (P < 0.01), and hypoxia-inducible factor 1α (P < 0.01) were greater in cows under Mod-HS than those under No-HS. Red blood cell count (P < 0.01) and hemoglobin concentration (P < 0.01) were lower in the coccygeal vein of dairy cows under Mild- and Mod-HS than those of cows under No-HS.ConclusionsExposure to HS negatively impacts the health status and lactation performance of dairy cows by limiting oxygen metabolism and transportation. However, the specific mechanism by which HS affects mammary function in cows remains unclear and requires further exploration.

High-pressure homogenization of olivine-hosted CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;-rich melt inclusions in a piston cylinder: insight into the volatile content of primary mantle melts

Abstract. Experimental homogenization of olivine-hosted melt inclusions representative of near-primary basic and ultrabasic magmas is a powerful approach to investigate the nature of their source regions and the melting conditions in Earth's mantle. There is growing evidence that the total CO2 contents of olivine-hosted melt inclusions may reach values of the order of a single to several weight percent, especially in intraplate continental basalts. To be able to homogenize melt inclusions with such high CO2 contents, we developed a technique allowing for heat treating of the melt inclusions under hydrostatic pressures up to 3–4 GPa in a piston cylinder, using thick-walled Au80–Pd20 containers and molten NaCl as the surrounding medium for the inclusion-bearing olivines. We applied this technique to olivine phenocrysts from Thueyts basanite, Bas-Vivarais volcanic province, French Massif Central. Thueyts melt inclusions were chosen because of their high CO2 contents, as indicated by up to 1.19 wt % dissolved CO2 in the glasses and by the presence of shrinkage bubbles containing abundant carbonate microcrystals in addition to a CO2 fluid phase. The homogenization experiments were conducted at pressures of 1.5 to 2.5 GPa, temperatures of 1275 and 1300 ∘C, and run durations of 30 min. In all the melt inclusions treated at 2.5 GPa–1300 ∘C and half of those treated at 2 GPa–1300 ∘C, we were able to completely homogenize the inclusions, as indicated by the disappearance of the starting bubbles, and we obtained total CO2 contents ranging from 3.2 wt % to 4.3 wt % (3.7 wt % on average). In all the other melt inclusions (equilibrated at 1.5 or 2 GPa and 1300 ∘C or at 2.5 GPa–1275 ∘C), we obtained lower and more variable total CO2 contents (1.4 wt % to 2.9 wt %). In the inclusions with the highest total CO2 contents, the size of the shrinkage bubble was in most cases small (&lt;5 vol %) to medium (&lt;10 vol %): this is a strong argument in favor of an origin of these melt inclusions by homogeneous entrapment of very CO2-rich basanitic liquids (∼ 4 wt %) at pressures of 2 to 2.5 GPa. The lower total CO2 contents measured in some inclusions could reflect a natural variability in the initial CO2 contents, due for instance to melt entrapment at different pressures, or CO2 loss by decrepitation. An alternative scenario is heterogeneous entrapment of basanitic liquid plus dense CO2 fluid at lower pressures but still at least on the order of 1 GPa as indicated by dissolved CO2 contents up to 1.19 wt % in the glasses of unheated melt inclusions. Whatever the scenario, the basanites from the Bas-Vivarais volcanic province were generated in a mantle environment extremely rich in carbon dioxide.

Low serum total CO2 and its association with mortality in patients being followed up in the nephrology outpatients clinic

Large-scale studies have not been conducted to assess whether serum hypobicarbonatemia increases the risk for kidney function deterioration and mortality among East-Asians. We aimed to determine the association between serum total CO2 (TCO2) concentrations measured at the first outpatient visit and clinical outcomes. In this multicenter cohort study, a total of 42,231 adult nephrology outpatients from 2001 to 2016 were included. End-stage renal disease (ESRD) patients on dialysis within 3 months of the first visit were excluded. Instrumental variable (IV) was used to define regions based on the proportion of patients with serum TCO2 < 22 mEq/L. The crude mortality rate was 12.2% during a median 77.0-month follow-up period. The Cox-proportional hazard regression model adjusted for initial kidney function, alkali supplementation, and the use of diuretics demonstrated that low TCO2 concentration was not associated with progression to ESRD, but significantly increased the risk of death. The IV analysis also confirmed a significant association between initial TCO2 concentration and mortality (HR 0.56; 95% CI 0.49–0.64). This result was consistently significant regardless of the underlying renal function. In conclusion, low TCO2 levels are significantly associated with mortality but not with progression to ESRD in patients with ambulatory care.

Influence of Medications Containing Acid Salts on Serum Bicarbonate in CKD

Many medications are formulated with acid salts. Their effect on acid-base balance in CKD is unclear. We calculated the acid load (meq/d) from medications prescribed to 74 United States veterans with diabetes and CKD to identify agents with high potential acid load. We also determined cross-sectional associations between the acid load from medications and acid-base parameters after adjusting for demographics, eGFR, protein intake, and other confounders. Of the 125 medications prescribed, 31 (25%) contained an acid salt. Metformin hydrochloride (15.4 meq/d at 2550 mg/d) and gabapentin hydrochloride (13.0 meq/d at 2700 mg/d) were identified as agents with a high potential acid load. Mean daily acid load from medications was 6.6 meq/d in the overall cohort, 14.2 meq/d in the high medication acid load group (≥7.7 meq/d, n=29), and 1.6 meq/d in the low medication acid load group (<7.7 meq/d, n=45). After adjusting for potential confounders, those in the high acid load group had 1.7 meq/L lower total carbon dioxide (CO2) and 2.2 meq/L higher anion gap than those in the low acid load group. Use of gabapentin alone was not associated with differences in total CO2 or anion gap. Use of metformin alone was associated with 0.7 meq/L lower total CO2 and 1.0 meq/L higher anion gap. Use of metformin with gabapentin was associated with 1.8 meq/L lower total CO2 and 2.4 meq/L higher anion gap. The higher anion gap was not explained by higher serum lactate levels. The acid load from medications was not associated with differences in urinary ammonium, titratable acid, or pH. Medications containing acid salts, particularly metformin hydrochloride and gabapentin hydrochloride, are sources of an exogenous acid load. These agents may influence serum total CO2 levels and serum anion gap in individuals with CKD. Investigations of the Optimum Serum Bicarbonate Level in Renal Disease, NCT01574157.

Non-diabetic glycosuria as a diagnostic clue for acute tubulointerstitial nephritis in patients with azotemia

Background Glycosuria is one of the manifestations of acute tubulointerstitial nephritis (ATIN), but may also be observed in other renal diseases. In this study, we investigated the value of non-diabetic glycosuria as a diagnostic clue for ATIN. Methods We retrospectively reviewed the medical records of adult patients who underwent a kidney biopsy as an evaluation for serum creatinine > 1.4 mg/dL. Patients with proteinuria in the nephrotic range, diabetes mellitus, or transplanted kidney were excluded. The laboratory abnormalities suggestive of tubular injury were compared between 28 patients (14 men and 14 women, mean age 48.5 ± 14.1 years) with ATIN and 116 patients (76 men and 40 women, mean age 53.1 ± 15.0 years) with other diagnoses. Results In ATIN, glycosuria (≥ 1+ on dipstick; 68%) was more frequent than hypophosphatemia (18%), hypouricemia (18%), hypokalemia (18%), and tubular proteinuria (40%). In other diagnoses, glycosuria (≥ 1+) was detected in 7 (6%) patients; 6 of them had the histological diagnosis of antineutrophil cytoplasmic antibody-associated glomerulonephritis. The presence of glycosuria (≥ 1+) had 68% sensitivity and 94% specificity for ATIN, with the positive likelihood ratio of 11.24 and the negative likelihood ratio of 0.34. Pyuria and low total CO2 were equally and more sensitive (68% and 71%, respectively) than glycosuria (≥ 1+), but had no diagnostic value due to low specificities (58% and 60%, respectively). Conclusion In non-diabetic, non-nephrotic patients undergoing a kidney biopsy for azotemia, 1+ or higher glycosuria, if present, was a good predictor of the diagnosis of ATIN.

Metabolic Acidosis and Long-Term Clinical Outcomes in Kidney Transplant Recipients.

Metabolic acidosis (MA), indicated by low serum total CO2 (TCO2) concentration, is a risk factor for mortality and progressive renal dysfunction in CKD. However, the long-term effects of MA on kidney transplant recipients (KTRs) are unclear. We conducted a multicenter retrospective cohort study of 2318 adult KTRs, from January 1, 1997 to March 31, 2015, to evaluate the prevalence of MA and the relationships between TCO2 concentration and clinical outcomes. The prevalence of low TCO2 concentration (<22 mmol/L) began to increase in KTRs with eGFR<60 ml/min per 1.73 m2 and ranged from approximately 30% to 70% in KTRs with eGFR<30 ml/min per 1.73 m2 Multivariable Cox proportional hazards models revealed that low TCO2 concentration 3 months after transplant associated with increased risk of graft loss (hazard ratio [HR], 1.74%; 95% confidence interval [95% CI], 1.26 to 2.42) and death-censored graft failure (DCGF) (HR, 1.66; 95% CI, 1.14 to 2.42). Cox regression models using time-varying TCO2 concentration additionally demonstrated significant associations between low TCO2 concentration and graft loss (HR, 3.48; 95% CI, 2.47 to 4.90), mortality (HR, 3.16; 95% CI, 1.77 to 5.62), and DCGF (HR, 3.17; 95% CI, 2.12 to 4.73). Marginal structural Cox models adjusted for time-varying eGFR further verified significant hazards of low TCO2 concentration for graft loss, mortality, and DCGF. In conclusion, MA was frequent in KTRs despite relatively preserved renal function and may be a significant risk factor for graft failure and patient mortality, even after adjusting for eGFR.

Nutritional Status in Adults with Predialysis Chronic Kidney Disease: KNOW-CKD Study.

Adverse changes in nutrition are prevalent and are strong indicators of adverse outcomes in patients with chronic kidney disease (CKD). The International Society of Renal Nutrition and Metabolism (ISRNM) proposed a common nomenclature and diagnostic criteria to identify protein-energy wasting (PEW) in CKD patients. We examined the nutritional status in 1,834 adults with predialysis CKD enrolled in the KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD) study. As there was a need for further understanding of nutritional status and associated factors in CKD, we evaluated the prevalence and associated factors of PEW in adults with predialysis CKD. The prevalence of PEW was about 9.0% according to ISRNM criteria and tended to increase with advanced stage in predialysis CKD. Those who concurrently had PEW, inflammation, and CVD were a small proportion (0.4%). In multivariate logistic regression model, PEW was independently associated with estimated glomerular filtration rate (eGFR) (odds ratio [OR], 0.98; 95% confidence interval [CI], 0.96–0.99), total CO2 (OR, 0.93; 95% CI, 0.87–0.99), physical activity (OR, 0.43; 95% CI, 0.26–0.69), comorbid diabetes (OR, 1.68; 95% CI, 1.09–2.59), and high sensitivity C-reactive protein (hs-CRP) (OR, 1.03; 95% CI, 1.01–1.06). Our study suggests that PEW increases with advanced CKD stage. PEW is independently associated with renal function, low total CO2, low physical activity, comorbid diabetes, and increased hs-CRP in adults with predialysis CKD.

Heterogeneous large total CO2 abundance in the shallow magmatic system of Kilauea volcano, Hawaii

Due to its very low solubility in silicate melts, CO2 concentrations in melt inclusions (MIs) within crystals are commonly orders of magnitude less than the total concentration in the multiphase magma, strongly limiting the possibility to constrain CO2 abundance based on the dissolved quantities. Here we develop a statistical method to process MI data, which allows analytical uncertainties to be taken into account together with the peculiar features of the local saturation surface. The method developed leads to retrieve total H2O and CO2 concentrations in magma as well as the gas phase abundance at the time of magma crystallization. Application to a set of 29 high‐resolution secondary ion mass spectrometry (SIMS) MI data from a single specimen of the 1842–1844 eruption of Kilauea, Hawaii, reveals the existence of heterogeneous total CO2 abundance, and of at least 2–6 wt % total CO2 in some magma batches, two orders of magnitude higher than the dissolved amounts and 30–50 times more abundant than the corresponding total H2O content. Heterogeneous total volatile concentrations are interpreted as due to a combination of degassing and gas flushing in magma subject to convective motion at shallow depth where P &lt; 100 MPa. In such a view, the magma rising to shallow depth in the volcanic system carries initially a total volatile content ≤1 wt %, corresponding to the determined low total CO2 population, and consistent with previous global estimates. The high CO2 populations correspond to progressive CO2 enrichment due to degassing at low P and flushing from a deep CO2‐rich gas. A total CO2 content &gt;1 wt % is likely to characterize the &gt;30 km deep magma, not represented in the analyzed inclusions, from which a CO2‐rich gas phase exsolves and decouples from the liquid.

Effects of partial and total colectomy on mineral and acid‒base homoeostasis in the rat: magnesium deficiency, hyperphosphaturia and osteopathy, in the presence of high serum 1,25-dihydroxyvitamin D but normal parathyroid hormone

The effects of colectomy on acid-base status, extra-osseous and bone minerals, calciotropic hormones and bone morphology have not yet been studied. To rectify this, groups of normally fed male rats were subjected to distal (n=11), proximal (n=12) or total (n=12) colectomy. Sham-operated rats (n=12) served as controls. At 112 (+/-2) days after colectomy the following changes were noted: (1) weight gain was delayed; (2) faecal excretion of calcium and phosphorus was normal, whereas that of magnesium was increased; (3) intestinal calcium secretion and absorption of calcium and phosphorus were normal, but magnesium absorption was decreased; (4) urinary excretion of magnesium was also decreased, that of phosphorus was increased, and that of pyridinium and deoxypyridinium tended to be high; (5) the serum levels of ionized magnesium, total calcium, 25-hydroxyvitamin D and parathyroid hormone were normal, while that of 1,25-dihydroxyvitamin D was markedly elevated; and (6) bone magnesium and phosphorus content were decreased, but bone calcium was normal, and thus the bone calcium/phosphorus ratio was high. These abnormalities were associated with moderate metabolic acidosis, as reflected by high urinary ammonium, low citrate and low total CO(2), but normal blood gases. Significant structural abnormalities of bone were not detectable, but trabecular bone tended to show rarefication. Distal colectomy had the least effect, whereas proximal and total colectomies had a distinct effect, on these parameters. It is concluded that colectomy in the rat causes: (1) a syndrome of magnesium deficiency of intestinal origin, compensated metabolic acidosis, urinary phosphorus loss, and high circulating 1,25-dihydroxyvitamin D levels, with the degree depending on the extent of surgical resection; and (2) brittle bones, a feature characteristic of low bone magnesium and more generalized magnesium deficiency. The mechanisms leading to this syndrome are unknown, but altered tissue levels of magnesium and phosphorus may play a key role.

Effects of partial and total colectomy on mineral and acid–base homoeostasis in the rat: magnesium deficiency, hyperphosphaturia and osteopathy, in the presence of high serum 1,25-dihydroxyvitamin D but normal parathyroid hormone

The effects of colectomy on acid–base status, extra-osseous and bone minerals, calciotropic hormones and bone morphology have not yet been studied. To rectify this, groups of normally fed male rats were subjected to distal (n = 11), proximal (n = 12) or total (n = 12) colectomy. Sham-operated rats (n = 12) served as controls. At 112 (±2) days after colectomy the following changes were noted: (1) weight gain was delayed; (2) faecal excretion of calcium and phosphorus was normal, whereas that of magnesium was increased; (3) intestinal calcium secretion and absorption of calcium and phosphorus were normal, but magnesium absorption was decreased; (4) urinary excretion of magnesium was also decreased, that of phosphorus was increased, and that of pyridinium and deoxypyridinium tended to be high; (5) the serum levels of ionized magnesium, total calcium, 25-hydroxyvitamin D and parathyroid hormone were normal, while that of 1,25-dihydroxyvitamin D was markedly elevated; and (6) bone magnesium and phosphorus content were decreased, but bone calcium was normal, and thus the bone calcium/phosphorus ratio was high. These abnormalities were associated with moderate metabolic acidosis, as reflected by high urinary ammonium, low citrate and low total CO2, but normal blood gases. Significant structural abnormalities of bone were not detectable, but trabecular bone tended to show rarefication. Distal colectomy had the least effect, whereas proximal and total colectomies had a distinct effect, on these parameters. It is concluded that colectomy in the rat causes: (1) a syndrome of magnesium deficiency of intestinal origin, compensated metabolic acidosis, urinary phosphorus loss, and high circulating 1,25-dihydroxyvitamin D levels, with the degree depending on the extent of surgical resection; and (2) brittle bones, a feature characteristic of low bone magnesium and more generalized magnesium deficiency. The mechanisms leading to this syndrome are unknown, but altered tissue levels of magnesium and phosphorus may play a key role.

Diabetic ketosis and ketoacidosis in cats: 42 cases (1980–1995)

Objective— To determine clinical signs, clinicopathologic abnormalities, prevalence of concurrent disease, treatment, complications of treatment, and outcome in cats with diabetic ketosis (DK) or diabetic ketoacidosis (DKA). Design— Retrospective study. Animals— 42 cats with DK or DKA. Procedure— Medical records of diabetic cats with ketonuria were reviewed. Results— In 26 cats, diabetes was newly diagnosed; in 16, diabetes had been diagnosed previously and cats had been treated with insulin (n = 14) or sulfonylurea drugs (2). Common clinical findings were lethargy, anorexia, polyuria, polydipsia, and weight loss. Common laboratory findings were hyperglycemia, hyponatremia, hypochloremia, hypokalemia, hypocalcemia, hypophosphatemia, low total CO2 content, hyperosmolality, high serum alanine transaminase activity, azotemia, glycosuria, and ketonuria. Concurrent disorders were identified in 39 cats and included hepatic lipidosis, cholangiohepatitis, pancreatitis, chronic renal failure, urinary tract infection, and neoplasia. Treatment of DK and DKA included administration of regular crystalline (34 cats), NPH (6), or ultralente (2) insulin, intravenous (38) or subcutaneous (4) administration of fluids, and enterall parenteral or administration of antibiotics (42). Complications during treatment included abnormalities in serum electrolyte concentrations (27 cats), hemolytic anemia (4), hypoglycemia (3), and neurologic abnormalities unrelated to hypoglycemia (2). Eleven cats died or were euthanatized during the initial hospitalization period for treatment of DK or DKA. Azotemia, metabolic acidosis, and hyperosmolality were more severe in cats that died than in cats that survived. Differences in regard to treatment or complications were not apparent between cats that died and cats that survived. The 31 cats that survived were discharged 1 to 16 days (median, 5 days) after initiation of insulin treatment. Diabetic ketosis or ketoacidosis recurred in 13 (42%) of these cats. Clinical Implications— A thorough diagnostic evaluation should be performed on cats with DK or DKA to identify concurrent disorders, formulate an appropriate treatment plan, and provide prognostic information to the owner. (J Am Vet Med Assoc 1997;211: 188–192)

Serum Electrolyte Patterns in End-Stage Renal Disease

The charts of 70 successive patients presenting for dialysis therapy for end-stage renal disease (ESRD) were evaluated for their serum electrolyte values. The "classical" pattern of low total CO2 (tCO2), elevated anion gap ("delta"), and normal chloride was found in a minority of patients (14 of 70, or 20%). Hyperchloremia was noted in 46%; in 21 patients (30%), this was associated with a normal delta and in 11 (16%), hyperchloremia was accompanied by an elevated delta. Fourteen patients (20%), most with diabetic nephropathy, had normal serum electrolytes. Patients with chronic glomerulonephritis had a hyperchloremic pattern as often as not, and two of four patients with interstitial nephritis demonstrated hyperchloremia without an elevated delta. We conclude that the previously held thesis that hyperchloremia is a rare or absent finding by the time renal failure progresses to ESRD is no longer tenable. Furthermore, a significant minority of ESRD patients may require the initiation of dialysis at a time when their serum electrolytes are still normal.

Evaluation of the Harleco Micro CO2 system for measurement of total CO2 in serum or plasma.

In the Harleco Micro CO2 System a volumetric procedure is used to measure total CO2 content in a small volume (0.10 ml) of serum or plasma. CO2 gas is released by mixing specimen and acid, either manually or with a "Micro CO2 Shaker." Within-batch CV's by manual and machine shakings were, respectively, 7.7 and 5.6% for a total CO2 value of 8 mmol/liter, decreasing to 2.0 and 1.4% for a value of 45 mmol/liter. Between-batch CV's were 8.0 and 7.1% at low total CO2, decreasing to 2.4 and 2.0% at high total CO2. Measurements were linear for values from 5 to 60 mmol/liter. Analytical recoveries at low and high concentrations were 97.7 to 98.9%. Correlation coefficients for results obtained with the Technicon "SMA Plus" autoAnalyzer and the Radiometer ABL 1 blood gas analyzer were 0.992 and 0.996, respectively. The Harleco Micro CO2 System appears to be a quick, reliable, and inexpensive method for measuring serum or plasma total CO2.

Eutrophication of Lake 227, Experimental Lakes Area, Northwestern Ontario, by Addition of Phosphate and Nitrate

Addition of 0.34 g P as Na2HPO4 and 5.04 g N as NaNO3 per square meter to a small unproductive Canadian Shield lake over a period of 17 weeks caused a severalfold increase in phytoplankton standing crop, and a change in dominant species from Chrysophyceae to Chlorophyta. Reactive phosphate concentrations remained at undetectable levels in the epilimnion after fertilization, and inorganic nitrogen concentrations remained low. Most of the added phosphorus and nitrogen was rapidly taken up by phytoplankton and sedimented with the seston.Although concentrations of total CO2 decreased to less than 20 μmoles/liter and pH values increased to greater than 9 in late summer, a high standing crop of phytoplankton was maintained. No marked increase in the rate of phytoplankton production was noticed Experiments in polyethylene containers suspended in the lake during this period of low total CO2 indicated that carbon was not limiting to algal production, except possibly at algal standing crops in excess of 100 μg/liter chlorophyll a, and that phosphorus was the primary limiting nutrient.Sodium added with the nutrients remained in the epilimnion until fall overturn, indicating that very little of it was utilized by phytoplankton.